i'm planning to go on the Norwegian Gem in June, which stops at Valleta, Civitavecchia, Naples, Livorno and Villefrance. for Valetta, i already know that i'm going to take a taxi to Mdina and explore there myself; for Villefrance, i'm going to take the rail to Monaco. however, i don't know what to do for Civitavecchia (Rome), Naples and Livorno.

i've heard that many people go on private tours for Rome, but that is outrageously expensive for my family of 4. would it be possible to explore this city by taking the rail from Civitavecchia to Rome and then walking? and what about Naples/Livorno? i guess i could go on cruise excursions for Naples and Livorno, seeing as they are not as expensive as private tours for Rome. does anyone have any recommendations?